How to use JavaScript to modify variable values

JavaScript is a widely used front-end programming language, often used to implement web page functions and interactive effects. In JavaScript, modifying variable values ​​is a very common operation. This article will introduce how to use JavaScript to modify variable values.

JavaScript variables

JavaScript variables are containers used to store data. In JavaScript, we can declare a variable using the var, let or const keywords. Among them, var is an early way of declaring variables, and let and const are new features introduced in ES6, which can better control the scope and variability of variables.

For example, the following is an example of using var to declare a variable:

var name = "张三";
var age = 18;
var isStudent = true;

In the above example, name, age, and isStudent are all variable names, and the right side of the equal sign is the initial value of the variable. The types of these variables are string, number, and boolean respectively.

Modify variable value

In JavaScript, the syntax for modifying variable value is very simple. Just use the assignment operator (equal sign) to assign the new value to the variable. For example, the following code demonstrates how to change the value of the variable age from 18 to 20:

age = 20;

In the above code, age on the left side of the equal sign is the variable name, and 20 on the right side of the equal sign is the new variable value. .

When the original value of the variable is a number, basic arithmetic operations can be performed, such as addition, subtraction, multiplication, division, modulus, etc. For example, if you want to add age to 5, you can use the following code:

age = age + 5;

What this means is that the value of the variable age is added to 5, and then the result is assigned to age. If you want to add 1 to the value of a numeric variable, you can also use the increment operator ( ):

age++;

This operator adds 1 to the original value and updates the result to the variable itself.

Another common way to modify variable values ​​is to use relational and logical operators. For example, the following code demonstrates how to use if statements and logical operators to determine the value of isStudent in order to update the value of the variable name:

if(isStudent == true){
  name = "小学生";
}

In the above code, if the value of isStudent is true, then the value of name is The value is changed to "elementary school student".

Summary

This article introduces how to use JavaScript to modify variable values. Although this operation is very simple, it is very commonly used and is the basis of JavaScript programming. If you want to learn more about JavaScript variables, check out the related tutorials and reference manuals.

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